Thread: Best way to get cold air to my Air Filter

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Cowl Induction Hood - How It Works...
Air glides over the cowl induction hood.
It then hits the base of the windsheild, creating a low pressure area, allowing the hot air to escape from the engine compartment.

Uhhh, Streets . . . I don't think so. Whoever put that on the PTeazer site flunked his fluids class. A VENTED cowl induction system will do what they say, but one of the old GM-style units operates on a different theory. The only excuse the PTeazer folks have is if the scoop opening is sufficiently far away from the windshield to create a siphon effect. The windshield doesn't have anything to do with their idea.

A vented cowl hood looks like a cowl induction hood from the 1960's but doesn't do the same thing. Cowl hoods like those on late 1960's Z28s were used to make more horsepower. Vented cowl hoods are designed to allow cooling air an easy escape path, allowing the engine to run cooler and possibly increasing stability by reducing the high pressure area under the nose of a car. The old cowl induction hoods used raised center section that ran back to the base of the windshield. Instead of having the opening on the front of the hood scoop, it was on the back. This allows the carb to pull its air from the relatively high pressure area at the base of the windshield, providing a very mild passive supercharging effect and possibly a few more horsepower. When a moving gas like air is brought to a halt, there is an attendant rise in pressure (the kinetic energy is converted to static pressure).

Bernoulli's equation illustrates this:
P + (rho*V**2)/2 = constant
where:
P = air pressure
rho = air density
V = air velocity

When you decrease the air velocity, pressure must increase to keep the quantity a constant.

Darkster . . .

Cowl induction is a rear facing scoop at the base of the windshield. (Cowel is that guy on American Idol, I think.) It works because the base of the windshield is a high pressure area. The car is trying to change direction of the air and force it over the top of the car. If there's an opening going to the carb, the air will go that direction. It's not "coming down the windshield" as you suggest. It's coming across the hood. When it hits the windshield, the velocity decreases, so the pressure must go up, not down. It's a very efficient way to get outside cold air to the carb.

Of course, you need the proper air cleaner, and a way to seal it to the inside of the hood.

- and is it necessary to turn every question into a poll?